Cathode ray tube manufacture



May 7, 1968 E. w. REINWALL, JR 3,381,347

CATHODE RAY TUBE MANUFACTURE 8 Sheets-Sheet 1 Filed Sept. 5. 1964INVENTOIR Ernest W. Renwall Jr.

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May 7, 196s E; w. REINWALL, JR 3,38L347 CATHODE RAY TUBE MANUFACTUREFiled Sep't. 5, 1964 8 Sheets-Sheet 2 FIG. 4

INVENTOR Ernest W. Reinw'all Jr.

29%/ gaa/ May 7, 1968 E. w. REINWALI., 1R 3,381,347

CATHODE RAY TUBE MANUFACTURE 8 Sheets-Sheet 5 Filed` Sept.

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I A ffl n. umn-Muffy annanL von raunnnaunnrinn INVENTOR Ernest W.Reinwoll Jr.

By fw May 7, 1968 E. w. REINWALL, JR 3,381,347

CATHODE RAY TUBE MANUFACTURE Filed Sept. 5. 1964 s sheets-sheet 4 FIG.I5

S mvENToR Ernest W. Reinwail Jr BY @2da/2M AHys.

Mayl 7, 1968 E. wQREINwALI.. JR 3,381,347

CATHODE RAY TUBE MUFAC'IURE 8 Sheets-Sheet 5 Filed Sept. 3. 1964INVENTOR Ernest W. Reinwall Jr.

May 7, 1968 E. w. REINWALL, JR 3,381,347

CATHODE RAY TUBE MANUFACTURE Filed Sept. s. 1964 s sheets-sheet eINVENTOR v Ernest w. Renwolldr May 7, 1968 E. w. REINWALL, JR 3,381,347

CATHODE HAY TUBE MANUFACTURE 8 Sheets-Sheet 7 Filed Sept. 3. 1964INVENTOR Ernest W. Reilnwull Jr.

May 7, 1968 E. w. REINWALL, JR 3,381,347

' CATHODE RAY TUBE MANUFACTURE Filed Sept. 5. 1964 8 Sheets-Sheet 8 FIG.l2

FIG. I4

2|2 o6 20e o 2|2 v INVENTOR Ernest W. ReinwcLlLJr.

Airys l United States Patent O M 3,381,347 CATHDE RAY TUBE MANUFACTUREErnest W. Reinwall, Jr., McHenry, Ill., assigner to Motorola, Inc.,Franklin Park, lll., a corporation of Illinois Filed Sept. 3, 1964, Ser.No. 394,152 6 Claims. (Cl. 29--25.13)

ABSTRACT 0F THE DHSCLOSURE This is a method for making a rectangularcolor cathode ray tube. The rearward constricted section of the tube .isinternally indexed and positioned within a collar extending about theoutside of the constricted section to establish a yoke reference plane.The edges of the forward flared section of the tube are ground flat at apredetermined distance from the yoke reference plane to form a paneledge plane perpendicular to the central geometrical axis of the tube.The funnel is then clamped in a neck sealing lathe using the panel edgeplane and the yoke reference plane to locate its position. The glassneck is flame sealed to the rearward section of the funnel with the neckbeing internally chucked and brought into alignment with the funnel bythe lathe mechanism. Three studs are inserted in the faceplate panel ofthe tube to establish a stud plane. The faceplate panel then is clampedin a fixture using the stud plane as a reference and the edges of theside walls are ground to define a panel edge plane parallel to the studplane. The panel is then frit sealed to the funnel by aligning the frontfunnel edge plane with the plane of the panel.

This invention relates to color cathode ray tubes and more particularlyto the structure and preparation of such tubes which incorporate ashadow mask and multiple electron beams for producing a composite imagein color.

In the widely used tri-beam shadow mask color picture tube, threecomplete sets of phosphor dots are arranged as the screen on thefaceplate panel of the tube. The three different sets of phosphor dotsemit respectively light of red, blue and green color when impinged by anelectron beam. Each group of three different phosphor dots is called atriad and is aligned with an aperture in a shadow mask so that the angleat which an electron beam passes through the mask will determine whichof the phosphor dots is impinged. Accordingly, three electron beams areswept scross the shadow mask and screen to produce an image the color ofwhich depends on relative excitation of the three dots in each colortriad.

In constructing a cathode ray tube of the above described type for usein a television receiver, it is necessary to form the faceplate panelwith its associated mask and phosphor screen as a subassembly and tosecure this to the funnel portion of the completed tube. Of course, theelectron gun structure which produces the three beams must also bepositioned in the neck of the funnel .and all of these parts arerequired to be exactly related in position within very stringentdimensional tolerances. Obviously each triad group of phosphor dots mustbe extremely small so as to be invisible to the unaided eye at anynormal distance from the tube, and the electron beams must be veryprecisely controlled in order to impinge only the proper phosphor dotsto avoid incorrect colors. Due to these stringent requirements on thedimensional accuracy and necessary associated structural rigidity of thecompleted tube, manufacturing costs of a color tube are substantial andthere are numerous production problems in commercially producingquantities of these tubes.

In the past it has been common to use glass of special hardness andthickness (as distinguished from the stand- 3,381,347 Patented May 7,1963 ard commercially available glass normally used in the manufactureof one gun black and white type cathode ray tubes which do not have ashadow mask) in order to maintain the dimensional tolerances duringmanufacture and to insure the proper alignment of the various tube partsfor correct color reproduction. Glass parts produced for black and whitetype tubes do not require the accuracy necessary for making shadow masktype color tubes. Black and white type tubes generally use soft glassmolded with relatively low dimensional tolerance and with the faceplatepanel sealed to the funnel prior to the application of the phosphorscreen. Accordingly, heretofore commercially available color picturetubes have not been made in production quantities using glass as thesoft type which is generally available for commercial manufacture ofblack and white type tubes.

In the past it has also been common to construct color cathode ray tubeswith round faceplate panels, rather than rectangular faces as is usualfor black and white type tubes. With a round tube face a portion thereofis masked off in order to approximate a more desirable raster shape andproportion for television viewing. The symmetry of a round face colorcathode ray tube can present some advantages in manufacture, whereas arectangular face tube, due to its lack of symmetry, has been found to bemore diflicult to manufacture and maintain the necessary dimensionalaccuracy and component alignment. Despite the possibly less difficulttask of manufacturing a round face color picture tube, it still has beencommon to utilize carefully dimensioned external ground indexing areason the tube parts as guides for assembling the various tube components.Furthermore, it has been frequently necessary to use special or hardglass which has been molded within precise dimensional tolerances inorder to permit satisfactory manufacture of tubes in substantialquantities.

lt is an object of this invention to provide a method of preparation andassembly of the parts of a color cathode ray tube having a rectangularface.

Another object is to improve the accuracy of color cathode ray tubesassembled in production quantities, without the need for external,ground index areas.

Another object is to insure the alignment of the electron gun structure,the shadow mask, and the phosphor screen in a color cathode ray tube,especially one having a rectangular faceplate panel.

A still further object is to use, in the production of color cathode raytubes, a funnel and faceplate panel composed of soft glass havingdimensional tolerances normally useful only in production of black andwhite type cathode ray tubes.

In a specic form of the invention the color cathode ray tube structureand process utilize a standard, cornmercially available glass panel,funnel, and neck of the type used in the manufacture of black and whitetype cathode ray tubes. The panel and funnel are dimensioned andprocessed, and the neck is assembled to the funnel, in order to comewithin the very close dimensional toler ances required for properoperation of a shadow mask type color tube, despite the fact that theseglass components in their initial state are unsuited for use in such atube.

An example of the glass usable in a black and white type tube, sometimesherein called soft glass, would be formed of lead-barium type glasseswhich typically have annealing points in the range of 430 C.460 C.,softening points in the order of 655 C. or less, and have a thermalcoefficient of expansion in the range of SS-lOOX l0*7/ C. One specificglass that is found to be successful is known as Kimble T lvl-5 glass(supplied by Kimble Glass Company, Toledo, Ohio) 'which has an anhealingpoint of 450 C., a softening point of 655 C.

J and a thermal coefficient of expansion of 90 10*'7/ C. from to 300 C.

The glass funnel, having a rectangular, flared forward section, and around, constricted rearward section, is clamped centrally of each sideof the forward section. The rearward section is internally indexed andpositioned within a collar extending about the outside of theconstricted section thereby establishing a yoke reference plane. Theedges of the forward ared section are then ground fiat within a givendistance from the yoke reference plane and perpendicular to the centralor longitudinal axis of the funnel so that the ground edges form a paneledge plane which is perpendicular to the axis. The funnel is thenclamped in a neck sealing lathe using the panel edge plane and aninternal centering plunger to locate its position. A glass neck is tiamesealed to the rearward section of the funnel with the neck internallychucked and brought into alignment with the funnel by the lathemechanism.

A rectangular faceplate panel, having depending side walls, is contouredon a mold in an oven in order that the panel and side walls will assumean exact contour and dimension. Three shadow mask mounting studs areinstalled in the panel side walls, with the panel still supported on itsshape determining mold so that these three studs accurately define astud plane with respect to the contour of the faceplate panel. Thisfaceplate panel is then clamped in a fixture with reference to the studplane, and the edges of the side walls are ground to define a panel edgeplane which is parallel to the stud plane and perpendicular to a centralaxis through the center of the panel as viewed from the front.

A shadow mask is supported by the studs during exposure of the threephosphor coatings to produce the groups of phosphor triads in thescreen. During this exposure operation the faceplate panel is indexed ona light exposure device with reference to the ground panel edge planeand three areas along the exterior periphery of the side walls of thepanel so that the nominal physical center of the panel appears on thelight source center line.

The funnel is then supported and the panel is placed thereon with theside walls visually aligned with the funnel so that the panel and funneledge plane and centers coincide for a frit sealing operation to assemblethe panel and funnel. Subsequently the electron gun structure isinstalled in the neck of the tube by supporting the tube in a saddle atthe yoke reference plane and jigging the tube neck about its peripheryand indexing the periphery of the faceplate panel as it was indexed inthe light exposure operation to produce the phosphor screen. The gunstructure may then be llame sealed within the neck as it is retained inproper position by this gun sealing jig. Finally the tube is finished byknown processes of exhausting the air, the sealing olf of the neck,activating the cathode, and the like.

In the drawings:

FIG. 1 is an elevational view of a color cathode ray tube constructed inaccordance with the invention;

FIG. 2 is a process How chart descriptive of producing the tube of FIG.1;

FIG. 3 is a plan, sectional view representative of a tube funnel clampedfor grinding;

FIG. 4 is an elevational sectional view taken along the line 4-4 of FIG.3 and including further portions of the apparatus not illustrated inFIG. 3;

FIG. 5 is a perspective view of lathe apparatus for iiarne sealing aneck to the funnel ofthe tube;

FIG. 6 is a perspective view of the neck chucking apparatus in greaterdetail than depicted in FIG. 5;

FIG. 7 is a sectional elevational View of a faceplate panel, its contourmold and a representation of stud installing apparatus;

FIG. 8 is a plan view of a portion of the apparatus for clamping afaceplate panel preparatory to grinding its edges;

FIG. 8a is a sectional view along the line Sa-Sa of FIG. 8;

FIG. 9 is a sectional view along the line 9-9 of FIG. 8, andillustrating further portions of the apparatus not shown in FIG. 8;

FIG. 10 is a partial elevational view showing the apparatus for lightexposing the phosphor screen of a faceplate panel;

FIG. 11 is a plan view of the apparatus of FIG. 10;

FIG. 12 is a plan view of a fixture for supporting the funnel and panelduring the frit sealing operation;

FIG. 13 is an elevational view of the fixture of FIG. 12;

FIG. 14 is an elevational view of a portion of the apparatus forsupporting the assembled panel and funnel during the installation of theelectron beam gun structure;

FIG. 15 is a sectional view along the line 15--15 of FIG. 14; and

FIG. 16 is a sectional view along the line 16-16 of FIG. 14.

In FIG. 1 there is shown a tri-gun, shadow -mask type color televisiontube 1) which may have a beam deliection angle, for example, of 92 and arectangular face of approximately 16.5 inches by 20.5 inches. The tube10 includes a base 12 with suitable electrical connectors wired to theelectron beam gun structure 14 which is disposed within the tube neck16.

An apertured shadow mask 18 is spaced from the phosphor screen 20 andsupported on the studs 22 melted into the side walls of the faceplatepanel 24.

The operation of the tube l() is generally understood in the art andinvolves the production of three electron beams by the gun structure 14which are modulated by video signals and which are deflected across thescreen 20 by suitable deflection apparatus. As representative, the beamassociated with the so-called red, blue and green guns of the device 14would travel the paths 26, 27 and 28 and pass through the aperturedshadow mask 18 to impinge respective phosphor dots 30, 3l and 32 whichform a triad, as previously discussed.

In FIG. 1 the longitudinal center axis of the tube is represented atline 40 and the yoke reference plane is represented by line 42 whichpasses through the constricted region of the funnel 44 perpendicular tothe axis 40 and at an area where the funnel is, for example, 21/2 inchesin diameter. The line 46 in FIG. l represents the juncture of the edgeplanes of the faceplate panel 24 and the funnel 44. Both of these planesare perpendicular to the axis 40. Line 48 represents the stud plane,which is also perpendicular to the axis 40 and passes through the threestuds 22, one on the top of the tube and one on each side, which alignand support the shadow mask 18.

The apparatus illustrated in FIGS. 3 and 4 represent a funnel jiggingand grinding mechanism to carry out funnel preparation 50 in FIG. 2 andmore particularly to establish the seal edge 46 at the proper distancefrom the yoke reference plane 42 and perpendicular to the funnel centerline 40. As previously stated the funnel 44 before treatment may havedimensions totally uniitted for the accuracy required in a color picturetube.

With the upper fixture 60 (FIG. 4) removed for clearance, the funnel 44is placed on the lower fixture 62. A spring biased centering plunger 65will engage the interior of the constricted portion of the `funnel inthe region of the yoke reference plane 42. The centering pads 67 and 68engage the interior of the forward or ared section of the funnelcentrally of each side thereof as shown in FIG. 3. The pads 67 arealigned along the minor axis of the front of the tube and the pads 68are aligned along the major axis of the front of the tube. The pads 67and 68 are mounted on respective spring loaded, self-centering linkagesto establish the physical center of the funnel and so that each of thepads is firmly engaged with the interior surface of the funnel, despitedimensional variaations therein.

As seen in FIG. 3, a rotatably mounted member 70 is spring biased in aclockwise direction and the ends of member 70 are pivotally joinedvthrough links 72 to the ends of the slide bars 74. The bars 74 carry thepads 67. As shown in FIG. 3, a corresponding linkage mechanism iscoupled to the pads 68 to perform a similar selfcenter ing function.

With the funnel 44 thus centered on the lower fixture 62, the upperfixture 60 (FIG. 4) is lowered to a fixed height so that this lfixturewill remain vertically locked throughout the remainder of the grindingoperation. The upper fixture 60 includes a centering yoke member 76which is mounted to permit lateral movement within the upper fixture,but which precisely locates the yoke reference plane 42 (FIG. 1) at aparticular diameter of the constricted portion of the funnel. Three ballrollers, one being shown as ball bearing 78 in FIG. 4, are disposedbetween the top of the member 76 and its mounting in the upper fixture60. These roller balls are disposed equally about the central axis ofthe upper and lower fixtures to define an exact plane, with the member76 bearing against and encircling the funnel neck, the spring biasedplunger 65 supporting the inner portion of the funnel on center, and theupper fixture 60 locked to a fixed vertical height.

At this point the centering pads 67 and 68 are locked in their springbiased positions against the interior of the funnel. A-s shown in FIG.4, Ithe air cylinders 82 operate a brake mechanism which drives thebrake pads 84 upwardly to lock the slide bars 74. The centering pads 68are similarly locked in position.

The exterior clamping pads 87 and 88 are locked against the outside ofthe forward portion of the funnel 44 opposite the location of thecentering pads 67 and 68. As FIG. 4 shows, the clamping pads 87 arepivotally mounted on the rocker arms 90 and these rocker arms arepivotally mounted to the upper fixture. Suitable pneumatic cylinders 92provide a mechanical drive for pivoting the rocker arms 90 so that thepads 87 are driven into engagement with the exterior of the funnel alongits minor axis and opposite the centering pads 67 which have beenpreviously locked in place. In the same manner pads 88 are positioned sothat the funnel is clamped preparatory to the operation for grinding itsforward edge.

Continuing with step 50 in FIG. 2 and with `the funnel 44 clamped asshown in FIG. 4, the upper fixture 60, the lower fixture 62, and thefunnel are rotated about the central axis of the apparatus by apparatusnot shown. Rotating grinding discs 96, diagonally spaced with respect tothe funnel cross section, are fed against the edge of the funnel toprovide a ground, seal edge (46) perpendicular to the center line of thefunnel.

In FIG. 4 there is a representative showing of the control of thegrinding disc 96. An electric motor 99 is slidably mounted on the shaft101 and a pivot-ally mounted lever 102 has one end connected to themotor and the lother end connected to a weight W and an air cylinder C.The cylinder C can apply an upward force to lower the motor after thegrinding operation while the weight W provides gravity drive of themotor upward so that the grinding disc 96 is fed -against the edge ofthe funnel. As much as one-eighth or one-quarter of an inch may beground from the edge of the funnel 44 in order that this edge will beestablished at a predetermined distance from the yoke reference planeestablished by the aperture in member 76.

The mounting for the electric motor 99 carries a projection 105 (FIG. 4)which engages a switch 107 when the grinding of the funnel edge hasprogressed to a point just short of the desired edge dimension. At thattime the switch 107 is closed to start the timer T which will permit themotor 99 to continue to operate for a predetermined time and then thetimer will retract grinding discs 96, turn off the motor and `causestopping of the Y rotation of the funnel in its supporting fixture. Itshould be understood that the apparatus shown associated with thegrinding motor 99 is represented schematically to facilitateunderstanding of its function. The other grinding wheel 96 in FIG. 4 isalso controlled in -accordance with the above description. Obviouslywhen the funnel has been ground, it is removed from the fixtures 60 and62 by reversing the previously described clamping operation. Aftergrinding the funnel is acid treated or fortified to remove any sharpsurface imperfections which could become focal points for latercracking.

FIGS. 5 and 6 represent the apparatus used in sealing the neck 16 on theconstricted portion lof the funnel 44 in the performance of step in theprocess of FIG. 2. The lathe 122 includes a flat head plate 124 having aspring biased centering plunger 126 projecting therefrom. The funnel 44is placed against the plate 124 and the plunger 126 centers the funnelby engaging it internally of its constricted portion. The ground edge ofthe funnel is held in contact with the plate 124 by means of clamps 128which engage the outside of the funnel at its corners. In this way theground edge of the funnel (46 in FIG. 1) is perpendicular to the centerline of 'the lathe and the center line of the funnel (40 in FIG. l)coincides with the center line of the lathe.

As best seen in FIG. 6, the tube neck is moved into place on the latheby a tail stock chuck 130. Movement of pivotally mounted handle 132 tothe left will cause sliding movement of the ring 134 to the rightagainst the compression spring 136. The cone 138 moves to the right withring 134 thus releasing the expansion pressure on the split collets 140and 141. The collets 140 and 141 are surrounded by garter springs whichwill cause them to collapse, or reduce in diameter so the neck 16 may beplaced as shown in FIG. 6. Then subsequent release of handle 132 willcause spring 136 to urge the ring 134 to the left and move the cone 138tothe left against the collet 141. Collets 140 and 141 slide to theleft, and are maintained in their spacing by means of a spacing collar143. A central spindle 146 of the tail stock is stationary and includesa conical portion against which the collet 140 is expanded. In this wayboth Collets 140 and 141 are compressed between the cones 138 and 146 toexpand and support the neck 16 on the centerI line of the lathe.

Referring again to FIG. 5, and with the neck 16 inside chucked asdescribed, the lathe mechanism is used to bring the neck to a positionagainst the constricted portion of funnel 44 so that the funnel and neckcan be flame sealed through melting of the glass by means of the burner149. During the flame sealing operation the lathe stocks are rotated andthe neck is thus secured in accurate alignment with the center line ofthe funnel. By reversing the above described setup procedure, theassembled funnel and neck may be removed from the lathe for laterassembly with the faceplate panel.

The process step 150 in FIG. 2 is carried out by means of apparatusillustrated in FIGS. 7, 8 and 9. The faceplate panel 24 is contoured,dimensioned and studded as illustrated schematically in FIG. 7. Thepanel 24 is placed on the contour mold 152 which is passed through asuitable oven so that the glass becomes soft and sags or drapes over themold surface to precisely contour the screen area of the panel. The mold152 additionally includes sizing areas 153 so that the side walls of thepanel t 24 will conform to these sizing areas thus accuratelydetermining the spacing between the side walls After emerging from thecontouring oven, the panel 24, still on the mold 152, is placed inapparatus for inserting the studs 22. While the panel 24 is hot from thecontouring operation, the studs 22 yare heated by means of radiofrequency energy and the arrns 155 are driven outwardly so that the heatfrom the studs 22 melts the glass in the side walls to permit them to bemelted into place (see FIG. 8a showing a stud completely installed). Theradio frequency energy is then turned off and the studs are held inplace while the glass resolidifies so that the studs 22 are preciselylocated with respect to an accurately contoured faceplate and its sidewalls. The studs 22, located about the side walls as shown in FIG. 8,thus define a stud plane 48 (FIG. l). The apertured shadow mask 18 canthen be accurately supported on the studs so that its distance andlocation with respect to the screen 20 is fixed.

As previously noted the faceplate panel 2-4 may be composed ofcommercial soft glass and/or glass which has not been originally moldedto sufiicient tolerance to enable it to be used in the color tube 10.Accordingly, the bottom edges of the side wall flanges are ground withrespect to the stud plane 48 so that this ground edge, 46 in FIG. l,will match the panel to the ground edge of the funnel. Thus furtherfaceplate panel preparation in step 150 involves the grinding of as muchas one-fourth to three-eighths of an inch from the edge of the side wallliange of the panel 24.

The panel 24 is located on the lower fixture 160 shown in FIG. 8 withthe studs 22 resting in the V-shaped stud supports 162 and on the flatstud support 163. These supports also align wtih the stud ends forlateral positioning of the panel. In this way the stud plane 48 will beaccurately located in the fixture 160, and, of course, the stud planehas been previously established with high accuracy with respect to thecontour of the face of the panel. FIG. 8a shows the detail of engagementbetween the top stud 22 and the flat rest pad 163. It may be noted thatthe rest pads are made adjustable and then capable of being locked intoplace when properly set.

With the panel accurately indexed on the grinding fixture, the upperfixture 165 (FIG. 9) is lowered to bring four spring biased pads 167into engagement with the top of the panel 24 in the region of eachcorner of the rectangular panel. Pads 167 are mounted on slidablemembers 168 which are spring biased by springs 169 towards the top ofthe panel. Accordingly all four pads 167 firmly engage the top surfaceof the panel. The members 168 are then locked in place by means of aircylinders 172 which apply pressure to the break pads 174, similarmechanisms control ea-ch pad.

The lower fixture 160 includes four pressure pads 176, one locatedimmediately under each of the top pressure pads 167. The pads 176 arepivotally mounted to the rocker arms 178 which are driven by the aircylinder 180 to pivot the pads 176 upwardly so that the panel 24 issandwiched between the pads 167 and 176.

With the panel 24 locked as depicted in FIG. 9, the upper fixture 165,the lower fixture 160 and the panel 24 are rotated by means not shownwhile the grinder wheels 183 are fed against the edge of the side wallsof the panel. The grinder wheels 183 are powered by electric motors 184which may be driven and controlled by apparatus representedschematically in FIG. 4. That is, the grinding wheels are gravity drivenagainst the panel edge until a predetermined stop is reached, at whichtime a timed finishing operation takes place to complete the side walledge perpendicular to the center axis 40 (FIG. 1) and parallel to thestud plane 48. When this edge has been completed, the grinding wheels183 are lowered, the rotation of the fixtures 160 and 165 is stopped andthe panel is removed by reversing the above described process. The panelis acid fortified to remove sharp edges.

Upon completion of panel preparation 150 in FIG. 2, the phosphor screenapplication 188 is carried out. In step 188 three different phosphorcoatings are applied to the interior of the panel 24, each coating isexposed in a lighthouse through the shadow mask 18, and it is developedto produce one of the sets of phosphor dots 30, 31 or 32. Moreparti-cularly a phosphor slurry of one light emitting type is depositedon the screen area 20 of the panel 24 and then dried. Shadow maskassembly 18 is inserted and the lighthouse exposure is made, which willbe described in more detail subsequently. Following the light exposurethe exposed set of phosphor dots is developed and the unexposed phosphoris removed, leaving a set of phosphor dots emitting a light of onecolor. The entire procedure is repeated twice more so that there arethree complete sets of the phosphor dots, for example, dots 30, 31 and32 in FIG. l. Since the production of the dots is associated with theparticular apertures of the shadow mask 18 the angle of approach of eachof the three electron beams will determine which dots are impinged byeach beam. This is a known and understood operation of a tri-beam shadowmask type color television tube.

Apparatus for performing step 188 is illustrated in FIGS. l0 and ll.After a phosphor slurry has been deposited on the interior of thefaceplate panel through procedures known in the art, shadow mask 18 isinstalled in the panel on the studs 22 and the panel is placed on thelighthouse exposure device 194. The device 194 has a reference centerline 195 with respect to which a point source of light is located tocorrespond to the location from which an electron beam would be producedfrom one of the three electron guns in the gun structure 14 (FIGURE l).For each of the three different operations for producing the separatephosphor dots the lighthouse apparatus 194 has a source of exposinglight positioned differently so that an exposure is made correspondingto the position of each of the three electron guns, one associated witheach of the three different prosphor coatings that are deposited on thescreen. This means that the beam from each gun in the gun structure 14will thus pass through the shadow mask 18 to strike only its intendedphosphor dots.

In order to assure that the phosphor dots are accurately located withrespect to the associated electron beam of the completed tube, the panel24 must be precisely indexed in the device 194. Accordingly the groundedge of the panel corresponding to the panel edge plane 46 is supportedon the four posts 193 to establish the distance between the screen ofthe panel and the exposing light source. Further to insure that thecenter line 195 of the lighthouse apparatus coincides with the nominalcenter line of the faceplate panel (line 40) there are three centeringposts 196 extending upwardly from the face 197 of the lighthouseapparatus. Two of the posts 196 engage the long side of the faceplatepanel 24 and one of the posts engages the short side. The lighthouseface 197 is disposed at an angle so that the weight of the panel 24 (itmay weight l5 pounds, for example) will cause it to nest against theposts 196. It will be noted that the side Walls of the panel 124 havebeen previously sized (FIG. 7) so that they are accurately spaced fromone another. It has been found that the wall thickness of the side wallsis sufficiently accurate that outside indexing of the panel on thelighthouse structure 194 will maintain a sufiicient accuracy forcoincidence of the panel center line 40 with the lighthouse center line195.

Further details in the performance of step 188 (FIG. 2) includelacquering of the completed phosphor screen and aluminizing of thepanel, as is familiar to those in the cathode ray tube art. The shadowmask 18 is then finally installed in the panel 24 and the panelsubassembly is glass soldered or frit sealed to the funnel 44 in thestep 200. FIGS. 12 and 13 show a xture or jig 202 for supporting thefunnel and panel as they pass through an oven to make the air tight sealalong the panel and funnel edge plane 46.

The frame or fixture 202 includes a loop 204 containing three equallyspaced, pivotally mounted supports 206. Supports 206 each carry carbonbuttons 207 which support the funnel in its relatively strong region,intermediate the front and back thereof. In addition there are fourcarbon buttons 210, which are mounted on manually adjustable thumbscrews so that the buttons 210 can be turned against the center of eachside of the front of the funnel 44 to prevent lateral movement thereof.The complete faceplate panel assembly 24 is diagonally centered upon theforward section of the funnel 44 with the ground edges thereof matedalong line 46. A fri-t sealing compound is deposited along the groundedges of these glass parts and the panel is laterally shifted foroptimum centering, which can be satisfactorily accomplished by visuallydetermining the best match across the diagonals of the panel and funnel.The wall thickness of the glass parts 24 `and 44 is accurate enough, andthe described apparatus is capable of sufficient accuracy, that matchingof the panel and funnel is well Within the necessary manufacturingtolerances. The four additional carbon buttons 212, which are alsomounted on adjustable thumb screws are then turned against the centersof the sides of the panel 24 to prevent lateral shift. With the paneland the funnel so aligned the assembly may be passed through an oven formelting the frit compound and soldering the parts together along theedge plane 46.

Step 220 (FIG. 2) involves installation and sealing of the electron gunassembly 14 within the neck 16 of the tube 10. Apparatus illustrated inFIGS. 14, l5 and 16 is used to properly support and index the tube forthis step of assembly. It is necessary that the gun structure 14 beaccurately aligned with the central axis 40 and positioned at apredetermined distance from the yoke reference plate 42.

The gun sealing fixture 230 includes a laterally movable saddle 233having an .aperture which supports the funnel 44 at its yoke referenceplate 42. The upper and lower neck centering chucks 236 and 237 are thenclosed to engage the tube neck 16 so that the tube is axially alignedalong its axis 40 Within the fixture 230.

As seen in FIG. 15 the fixture 230l includes a fixed rotationalalignment pin 238 which bears against the side wall of the panel 24 inthe same location that post 196 engages the panel (FIG. 1l). A rotatingalignment pin 239 is then moved in a clockwise direction against theopposite side wall of the panel 24 and locked in this position so thatthe tube is secured against rotational movement during the gun sealingoperation 220.

FIG. 16 shows a plan view of the upper neck centering chuck 236. Thischuck includes jaws 244 equally spaced about 4the tube neck 16 andradially slidable forward and away from the neck. A cam plate 246 isrotatably mounted and includes slots 248 into which the jaw mounted pins250 extend. Thus it may be seen that rotation of the cam pla-te 246 willchange the relative radial positions of the jaws 244.

Member 25-2 is coupled to the cam plate 246 `and is coupled throughspring 251 to the control handle 253. The handle 253 is slidably mountedso that moving this down in FIG. 16 will bring the compression spring251 .against the member 252 and cause cam plate 246 to move in a counterclockwise direction thereby closing the jaws 244 into engagement withthe neck 16. A suitable locking clamp (not shown) for the handle 253will therefore maintain a spring controlled pressure on the jaws 244 foraxially aligning the tube neck within the gun sealing fixture 230. Lowercentering chuck 237 may be similarly constructed.

With the 4tube 10 axially centered and located with respect to the yokereference plane and secured against rotational movement, the upper clamp255 (FIG. 14) is lowered so that the clamping pad 257 engages the faceof the panel 24. The clamp 255 includes a universal joint 258 so thatthe pads 257 will securely engage 4the faceplate panel and prevent anyvertical movement of the tube. It may be noted that the clamp 255 willsecure the tube in the floating yoke saddle 233.

The electron gun holder 260 is precisely located on the center line ofthe fixture and includes sutiable apertures (not shown) to engage thepins of the electron gun struc ture 14 and properly center it in thefixture 236. The rotational position of the electron gun structure mustcoincide with the different positions of the light sources in thelighthouse apparatus 194 and this is accomplished in the gun support269. The pin 261 further centrally aligns the gun structure on thefixture so that the holder 260 and gun can be moved upwardly into acentral position within the neck 16 of the tube. The electron gunstructure is moved upward until its support engages the stop surface 263which accurately determines the axial position of the gun with respectto the yoke reference plane 42. With the gun structure thus positioned,the lower centering chuck 237 is released and moved clear of the openend of the neck 16 while a flame sealing apparatus (not shown) isbrought up to this area for melting the glass at the neck and securingthe gun structure in place. During -this operation the fixture 230 isrotated about its central axis for uniformly forming the glass gun seal.

With the gun installation step 220` complete ('FIG. 2) variousadditional tube finishing steps 2120` are performed. These finishingsteps include the known and understood processes of pumping the tube toa vacuum, baking it in an oven, and sealing off the gun tip. There arefurther conventional steps of activating the cathode, installing theBakelite base on the connector pins of the gun structure and the like,elaboration of these additional steps not being necessary inunderstanding the processes and structure described herein.

The process and structure described in the foregoing permit theestablishment of a locating central axis through the tube parts and thefinished cathode ray tube in order to assist in manufacture and assemblyof such a tube with a rectangular faceplate. Furthermore, it is possibleto utilize glass parts which have only dimensional tolerances suitablefor black and White one gun picture tubes, and to process these parts sothat they can be assembled with precision and on a production basis forthe manufacture of a tri-gun shadow mask type color picture tube.Through the use of the described process and fixtures or jigs formachining and assembling the parts, very stringent dimensionaltolerances can be maintained so that the tubes operate properly withoutundue beam landing errors, while still maintaining a desirably highproduction yield.

I claim:

1. A process for producing a color picture tube, including the steps of:providing a glass funnel having a for- Ward section and a constrictedrearward section with a central axis extending therethrough,establishing a yoke reference plane in the region of said rearwardsection and perpendicular to said central axis, forming an edge of saidforward section at a specified distance from said yoke reference plane,providing a faceplate panel having side walls depending therefrom,forming the edge of said side walls in a single plane at a specifieddistance from the face of said panel, applying a phosphor screen to saidpanel by reference to the edge of said side `walls and to an axisthrough said panel perpendicular to the plane of the edge of said sidewalls, joining said funnel to said faceplate panel with the edgesthereof abutting one another, and installing an electron gun structurein said constricted section aligned with the central axis and spaced agiven distance from the yoke reference plane.

2. A process for producing an envelope for a color picture tube,including the steps of providing a glass funnel having a forward sectionand a constricted rearward section, said funnel having a centrallongitudinal axis and a yoke reference plane perpendicular to said axisin the region of said rearward section, grinding the edge of saidforward section to a given distance from said yoke reference plane andperpendicular to said central axis, providin g a faceplate panel withshadow mask mounting studs on the interior side walls thereof, saidstuds being indexed with respect to the contour of the face of saidpanel, grinding the edge of the side walls of said panel to a specilieddistance from the face of said panel and in a plane l l. parallel tosaid stud plane, and joining the ground edges of said panel and saidfunnel with the side walls and the forward section aligned to provide apicture tube envelope.

3. In producing a faceplate panel for a color picture tube the steps of:providing a faceplate panel having side walls depending therefrom andshadow mask supporting studs disposed in said side walls inpredetermined relation with respect to the face of said panel,supporting said panel on said studs, applying spring biased pads againstthe outer surface of said panel, locking said pads in fixed relationagainst said panel, clamping the inner surface of the face of said panelagainst said pads, and grinding the edge of said side Walls to form aplane providing a reference with respect to said studs and the face ofsaid panel so that a phosphor screen may be applied to said panelreferenced to the ground edge of said side walls.

4. A process for producing a color picture tube, including the steps of:providing a glass funnel having a forward section and a constrictedrearward section, said funnel having a central longitudinal axis and ayoke reference plane perpendicular to said axis in the region of saidrearward section, grinding the edge of said forward section to a givendistance from said yoke reference plane and perpendicular to saidcentral axis, providing a faceplate panel with shadow mask mountingstuds on the interior side walls thereof, said studs being indexed withrespect to the Contour of the face of said panel, grinding the edge ofthe side walls of said panel to a specified distance from the face ofsaid panel and in a plane parallel to said stud plane, applying aphosphor screen to said panel referenced with respect to the ground edgethereof and the contour of said side walls, sealing the ground edges ofsaid panel and said funnel with the side lwalls and the forward sectionof said funnel in alignment, and installing an electron gun structure insaid constricted section aligned with said central axis at a givendistance from said yoke reference plane.

5. In the manufacture of cathode ray tubes the process for producing arectangular screen color picture tube, including the steps of: providinga glass funnel having a rectangular forward section and a round rearwardsection, clamping said forward section centrally of each Side thereof,center indexing said rearward section within a collar to establish ayoke reference plane thereabout and a funnel central axis, grinding theedges of said forward section to a given distance from said yokereference plane and perpendicular to said funnel center line, amesealing a glass neck to the rear end of said funnel with the neck andthe rearward section internally aligned along the funnel central axisand the ground funnel edge perpendicular to the neck, providing afaceplate panel with three Shadow mask mounting studs on the interiorside Walls and indexed with respect to the contour of said panel toestablish a stud plane, clamping said panel With respect to the studsand grinding the edges of said side walls of said panel to a specifieddistance from, and parallel to, said stud plane, applying a screen tosaid faceplate panel referenced to the ground edges thereof and to theperiphery of the side walls thereof, sealing the ground edges of saidfaceplate panel and said forward section of said funnel with said funnelforward section and the side walls of said panel in alignment acrossdiagonals thereof, and installing an electron gun structure indexed tosaid yoke reference plane and said neck.

6. In producing a funnel for a color picture tube the steps of:providing a glass funnel having a forward section and a constrictedrearward section with a geometric central axis extending therethrough,aligning said funnel on a spring biased central plunger and engagingsaid forward section internally thereof on spring biased selfcenteringlinkage arms mutually extendable to engage and position at the geometriccenter thereof the interior surface of said funnel adjacent said forwardsection, locking the linkage arms, clamping the outside of said forwardsection against the linkage arms, grinding the edge of said forwardsection perpendicular to the geometric central axis and at a givendistance from a yoke reference plane in the region of said rearwardsection, aligning the ground funnel on a spring biased central plungerand clamping the ground edge thereof in a neck sealing lathe so that thefunnel turns about the geometric central axis, chucking a tube neck inalignment with said rearward section and joining said neck to saidfunnel.

References Cited UNITED STATES PATENTS 2,373,932 4/1945 Waters 51-283 X2,700,255 1/1955 Meier 51-283 X 2,821,812 2/l958 Vermaas 65-57 2,871,037l/l959 KnOChel.

3,002,645 10/1961 Kegg 65--58 X 3,190,738 6/1965 Upton 65-61 X 3,291,58912/1966 Born 65-58 X WILLIAM I. BROOKS, Primary Examiner.

